+100%
No change
NORTH
AMERICA
SOUTH
AMERICA
EUROPE
TROPIC OF CANCER
TROPIC OF CAPRICORN
EQUATOR
ASIA
AFRICA
AUSTRALIA
–100%
the mosquito world, males live off plants. The
female is the biter, the worker, the source of hu-
man peril; she lives off plants too, but all those
blood nutrients are for her eggs, the nourishing
and laying of which are the great project of her
short, purposeful, and somewhat solitary life.
A single mating may be all an Ae. aegypti needs;
she stores sperm inside her body, fertilizing sep-
arate batches of eggs as needed, up to several
hundred at a time. Five or six occasions of egg
laying are common for an Ae. aegypti that es-
capes extermination by swat or insecticide and
reaches her expected month-long life span. The
multiplication possibilities are staggering.
Ask biologists what natural advantage dif-
ferent mosquito species might have gained by
spreading disease—why Aedes became the pri-
mary carrier of the Zika virus, for example, and
Anopheles the carrier of malaria parasites—and
they’re likely to tell you that you’re thinking
about the question backward. It’s the patho-
gens, those disease-causing organisms driven
to multiply in mammalian bodies, that over
Aedes aegypti
Found in cities,
this insect feeds
almost exclusively
on human blood.
Aedes albopictus
The aggressive, adapt-
able species can easily
colonize the habitats of
other mosquitoes.
Anopheles*
The only genus that
transmits malaria,
it is known for its
long front feelers.
Haemagogus*
These forest vectors
of yellow fever can be
identified by their
metallic sheen.
Mosquito Maladies
Pathogens have adapted to thrive in
different species of mosquitoes with
characteristics that make them good hosts.
Culex quinquefasciatus
These night feeders,
common around the
world, prefer to lay eggs
in dirty water.
LYMPHATIC
FILARIASIS
This tropical
disease alters the
lymphatic system
and causes
devastating
disfigurement and
enlargement of
body parts.
MALARIA
The parasitic
disease killed
more than
400,000 people in
2015. Most of the
fatalities were in
sub-Saharan
Africa.
WEST NILE
FEVER
In 1999, the
appearance of
this virus in the
U.S. highlighted
the threat of
vector-borne
diseases outside
native ranges.
DENGUE
FEVER
Spreading since
the 1970s, the
potentially fatal
virus now
threatens
50 percent of
the world’s
population.
YELLOW
FEVER
Nearly 60,000
deaths a year
are attributed
to this skin-
yellowing
disease, which
can be prevented
with a vaccine.
ZIKA VIRUS
DISEASE
This rapidly
spreading virus
can cause
defects in the
unborn babies
of infected
pregnant
women.
CHIKUNGUNYA
Named after a
Kimakonde word
meaning “to be
contorted,” the
virus, discovered
in Tanzania,
causes severe
joint pain.
JASON TREAT, RYAN WILLIAMS, AND CHARLES PREPPERNAU, NGM STAFF
SOURCES: WORLD HEALTH ORGANIZATION; CENTERS FOR DISEASE CONTROL AND PREVENTION (GRAPHIC); YIANNIS PROESTOS, CYPRUS INSTITUTE (MAP)
millennia “learned,” evolutionarily speaking,
what excellent transport and delivery services
some mosquitoes happen to provide. It’s not
an easy ride for the pathogens: They have to
survive being sucked into a mosquito’s gut, ex-
posed to digestive enzymes, and then pushed
through membranes into a mosquito salivary
gland before being injected into the next warm-
blooded host. The injectors, on the other hand,
are simply perpetuating their family line. “It’s
such a rare confluence of evolution that has
allowed this to happen,” says Karl Malamud-
Roam, a mosquito research scientist who helps
direct a pest management program based at
Rutgers University. “It’s hard to be a successful
germ or mosquito.”
A modicum of respect seems in order, then,
for this remarkable confluence and the very
resourcefulness of the flying vampires. Con-
sider the reproductive strategies of Aedes
aegypti, which because of Zika has been the
subject of international symposia and plans of
attack. An Ae. aegypti will lay her eggs in the
* Many species within the genus can transmit the disease.